Building a JCM 800 preamp. Should I add a stage after the MV, like an FX Send ?

[Iplayloud]

I really like to test and tweak mods in a plexi-JCM 800 preamp, but I sold the "frankenstein" amp I was using so now I just want to build a preamp and run it into my other amps.

I was wondering if I can stop the circuit right after the master volume or if I should add a stage after, apparently to run pedals better ?

If I don't plan on using pedals, but just to run it in the effects return of other amps what do you guys recommend?

I'm talking about a typical Marshall 2203 circuit. Thx!

[Iplayloud]

I'm talking about a typical Marshall 2203 circuit. Thx!

This stereo JCM 800 preamp here, finishes right after the EQ and MV: http://el34world.com/projects/images...pschematic.gif

I have heard that to drive pedals it's better to en the circuit with a FX send style output stage like this: http://www.blueguitar.org/new/schem/...wk_quattro.gif


I just wanted to have opinions on both options if anyone has something to say Thx!

[exclamationmark]

I usually run an op-amp buffer directly after the volume pot in all my pre-amps (I also use balanced line transformers to isolate possible ground loops). The reason that I put a buffer there is that the source impedance of the pre-amp will be huge compared to whatever you're driving, and it can sometimes lead to dull treble response, depending on how the effects loop of the amp you're plugging into is constructed. For example, in a 6505+ 112 combo that I like to hijack the power amp of, source impedance makes a HUGE difference - it goes from overly harsh to ridiculously dull depending if I buffer the output or not. I've thought this may be to do with the miller effect, but the grid leak should effectively shunt any source resistance to ground. Regardless of this, it's still a good idea if you want to drive line level interfaces (such as your sound card). Just make sure to attenuate the signal to suitable levels.

[Iplayloud]

I usually run an op-amp buffer directly after....

The second schematic link that i put uses a tube stage buffer and a pot, do you think that would give a decent adjustment range? And do you think it would definitely create ground loop problems?